1. Field of the Invention
This invention relates to turbine apparatus and in particular to an improved outer cylinder arrangement for a low pressure turbine apparatus.
2. Description of the Prior Art
As is well known to those skilled in the turbine art, any shutdown of a turbine apparatus for repair or replacement of damaged parts is a major cost to the operating utility. Especially troublesome is the repair and replacement of a damaged rotating blade from the last blade row within a low pressure turbine element.
The rotating blades in the last blade row of the low pressure turbine element are subject to vibratory energies which may sometimes result in damage thereto In addition, the rotating blades in the last blade row are also subjected to impingement by relatively large water droplets carried by the steam flow. This erosive environment may cause blade damage.
When replacement of damaged blades in the last rotating blade row in the low pressure turbine apparatus is necessary, due to vibration damage, erosion or any other reason, a time consuming and therefore costly shut-down period is required in order to repair the damaged blades. In the prior art, blades in the last rotating blade row in a low pressure turbine apparatus are repairable only after the outer and inner cylinders of the low pressure turbine element is removed.
Removal of the outer and inner cylinders of the low pressure turbine element is required in order to facilitate access to the damaged blades by repair personnel. It is evident therefore, that providing an outer cylinder for a low pressure turbine element which permits removal of damaged turbine blades from the last rotating blade row without necessitating a removal of the outer or inner cylinders of the turbine reduces the period of turbine down-time considerably. This, of course, reduces the period of unavailability of the turbine-generator unit, thus resulting in a significant cost savings.